Iso/dd image mounting howto

Howto to mount an dd/iso image

When disk fail/start failing it is sometimes necessary to create a backup of the hard drive using ddrescue (see ddrescue). This creates a bit for bit copy of the disk/file system.

To read the image you mount it via loopback

sudo mount -o,loop image.dd /mnt/point

you might need to specify the file system e.g.

sudo mount -o,loop -t ntfs image.dd /mnt/point

If this complains about not being able to find a file system it might be that a copy was made of an entire disc rather than partitions with in it.

In this run the command mmls -- this will output the partition table of the disk. Look up the number of the partition user the Start column.

This is a number expressed in blocks. Typically a block is 512 bytes so multiple this number by 512 to get the offset.

sudo mount -o,loop,offset=[number] image.dd /mnt/point

e.g. sudo mount -o,loop,offset=1048576 image.dd /mnt/point

You can also do e.g.:

sudo mount -o,loop,offset=$(2048 * 512 | bc) image.dd /mnt/point

In this case $(2048 * 512 | bc) is doing the multiplication for you.

This technique also works with iso images.

For use with Macs, and more details on mmls see:Mac Backup Notes